In 2006, Congress mandated the Secured Freight Initiative to test the feasibility of inspecting 100 percent of cargo containers coming from overseas for terrorist threats. The Department of Homeland Security (DHS) and the Department of Energy (DOE), in cooperation with maritime industry and foreign government partners, have already launched Phase I of the Secure Freight Initiative (SFI) to deploy a globally integrated network of radiation detection and container imaging equipment to be operated in seaports worldwide. The purpose of the initiative is to prevent terrorists from using nuclear or other radiological materials to attack the global maritime supply chain or using cargo containers to bring the resources for such an attack to the United States. DE-FG02-06ER84516
However, for Secure Freight to succeed, it must balance enhanced container security with an imperative to facilitate efficient global trade. Such a balance in an incredible challenge given that over 20 million shipping containers enter the U.S. each year. Economic considerations require that they be quickly unloaded by crane onto trucks and trains, and only a few percent are inspected.
The risk posed by the smuggling of special nuclear material or a nuclear weapon in cargo containers is obvious. In December 2005, the Department of Homeland Security (DHS) Domestic Nuclear Detection Office (DNDO) issued a Call for Proposals (CFP) that has a section on “long-dwell, in-transit radiation detection in large cargo-container ships.” In the introduction, this CFP states “For example, few effective, affordable, near-term technological solutions have been identified for robust detection and verification of shielded special nuclear material at our nation's ports of entry.”
The main problem with inspecting stacked cargo containers is inaccessibility; a large fraction of stacked containers cannot be inspected because they are surrounded on all sides by many tons of other containers and cargo. Inspection methods currently used or proposed involve unloading containers from ships and inspecting them individually. Most current research in this area also involves inspecting individual sealed containers using large external equipment. It is not clear whether these methods are fast enough for a sensitive inspection during container loading or unloading or whether they can permit repeated measurements without disrupting the flow of containers. These methods are extremely time-consuming, and thus, expensive, even when only a small sampling of containers is inspected. Furthermore, inspecting a small sampling is not enough to ensure that all cargo is safe. What is needed is an inspection system that can inspect every container when they are stacked, such as during the long times cargo is stacked (i.e. in a port, waiting area or while at sea).